Look, ma–it’s almost terrestrial!

Here’s a lesson in not procrastinating: by this point, everybody else has already quite effectively covered the various awesome species of algae that Emily enlightened us to at Cattle Point.  But, luckily for me, the species I found most interesting was not an alga.  Unsurprisingly, it was Phyllospadix scouleri, surfgrass (see Sucia blog re: one-trick pony).

Surfgrass seems to be a pretty unique plant, both as terrestrial and marine plants go.  It’s one of the only angiosperms that can withstand being battered by the harsh conditions of the intertidal (hence the common name “surfgrass”), and also has a unique reproduction system.  A dioecious plant, surfgrass produces barbed seeds (below) which entangle themselves into nearby red algae and germinate immediately.  This is probably the coolest biology factoid I have heard.  Or at least the coolest one that comes to mind.

Barbed seeds (not fully developed) and sheath.

Barbed seeds (not fully developed) and sheath.

Surfgrass (far right) next to red algae next to barnacles.  Also a good example of zonation.

Surfgrass (far right) next to red algae next to barnacles. Also a good example of zonation.

But, even more interesting than that (“Not possible!” I hear you cry) are the results of a 1995 study by Susan Williams examining the distribution and ratios of sexes in Phyllospadix scouleri.  Williams was interested in the previously noted strong female bias among populations of Phyllospadix, as, though males are scarce, pollen is not.  There is a theory in ecology that in dioecious plants, the more energy-intensive sex to produce will be less competitive, thereby skewing the sex ratios.  Williams found that male reproductive organs were only slightly, but not statistically, higher than female reproductive organs, thereby demonstrating how even slight energy allocation differences can result in dramatic effects at the population level.  There is also a marked difference in the distribution of sexes; within the surfgrass bed, females are found in shallower waters while males prefer the deep end of the pool.  There are a few hypotheses as to why males are more competitive at deeper depths, including that the more continuous submersal facilitates pollen dispersal, and that, for unexplained reasons, the males are less strongly attached than females and therefore do better in less turbid subtidal zone.   Females, on the other hand, are fitter under more intense light conditions.


PS Just for kicks…




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